<!DOCTYPE html>
<html lang="zh-CN">

<head>
    <meta charset="UTF-8">
    <title>03_修改元素的显示模式</title>
    <style>
     #d1,#d3 {
         background-color: aqua;
         display: inline-block;
     }
     #d2 {
         background-color: aquamarine;
         display: inline-block;
     } 

     span {
         background-color: red;
         display: block;
     }
    </style>
</head>

<body >
    <div id="d1">1</div>
    <div id="d2">2</div>
    <div id="d3">3</div>
    <span>人之初</span>

    <span>性本善</span>
</body>

</html>